The present invention relates to a hot rolling method and equipment. More particularly, it relates to a hot rolling method and equipment which are suitable for being used when rolling is performed by joining the tail edge of a preceding material and the leading edge of a following material to each other during traveling and supplying the materials to a rolling mill continuously, and which are capable of stably joining the preceding material and the following material to each other during traveling.
Conventionally, on a hot rolling line, a plurality of slabs to be rolled have been heated in advance, and after the completion of heating, the slabs are rough rolled and finish rolled one after another to give a hot rolled plates a desired thicknesses. With this method, the line is sometimes stopped by poor biting of rolled material in finish rolling. Also the yield greatly decreases because of odd shapes of the leading edge and tail edge of the rolled materials. For this reason, in recent years, a rolling method has been used in which the tail edge of a preceding metal block and the leading edge of a following metal block are joined to each other during traveling and the joined material is supplied to a finish rolling mill continuously.
For example, Unexamined Japanese Patent Publication No. 7-1008 relating to a joining method of plates with continuous rolling equipment has disclosed a joining method. In this joining method, to start with, a distance between the tail edge portion of a preceding plate and the leading edge portion of a following plate is made zero by colliding the opposing faces with each other so as to form a required distance accurately and easily, to improve the heating performance of the opposing faces and to obtain a fine joined portion, and then either the preceding plate or the following plate is moved to form the distance between the plate edge faces. Subsequently, an alternating magnetic flux is applied to the edge portion of those plates in the thickness direction, an eddy current is induced in the respective portions to heat them by Joule heat, and the edge portion of those plates is pushed to each other by pressurizing means to complete joining.
Also, Unexamined Japanese Patent Publication No. 6-226320 has disclosed a technique in which when to extract slabs from heating furnaces are controlled in order that plates after rough rolling are joined accurately at a predetermined position and rolled continuously.
Further, Unexamined Japanese Patent Publication No. 7-188785 relating to a hot rolling method in which plates are not joined has disclosed a method of controlling extraction pitches from heating furnaces properly. In this method, the extraction pitches are controlled to appropriate values so that the temperature of heated materials be kept the same in spite of unexpected change of the condition of rolling line and a sudden change of furnace temperature is restrained.
However, the above-described conventional methods are not sufficient for making a following metal block catch up with a preceding metal block and for joining each other during traveling by a movable joining apparatus.
An object of the present invention is, on a hot rolling line, to make following metal block catch up with preceding one and to obtain stable joining.
To achieve the above object, the present invention provides a hot rolling method in which the tail edge of a preceding material and the leading edge of a following material are joined to each other during traveling by a movable joining apparatus after hot rough rolling, and the joined materials are fed to a finish rolling mill to be rolled, characterized in that the speed of the following material is controlled according to the position of the tail edge of the preceding material so that a distance between the tail edge of the preceding material and the leading edge of the following material become a desired value, whereby the tail edge of the preceding material and the leading edge of the following material are joined to each other during traveling.
Also, in the hot rolling method, an (aiming) distance between the tail edge of the preceding material and the leading edge of the following material is determined in advance as a function of at least the moving tail edge position of the preceding material, the actual tail edge position of the preceding material is measured, the (aiming) distance between the tail edge of the preceding material and the leading edge of the following material is determined from the measured tail edge position of the preceding material and the function, and the (actual) position of the leading edge of the following material is controlled by the speed of the following material so as to obtain the distance, whereby the leading edge of the following material approaches and joins the tail edge of the preceding material while the preceding material is traveling.
Also, in the hot rolling method, the speed of the following material is controlled according to the position of the tail edge of the preceding material so that a distance between the tail edge of the preceding material and the leading edge of the following material become a desired value, and the traveling speed of the joining apparatus is controlled so that a determined point in the moving joining apparatus coincide with the tail edge of the preceding material, whereby the leading edge of the following material approaches and joins the tail edge of the preceding maternal while the preceding material is traveling.
Also, in the hot rolling method, a distance between the tail edge of the preceding material and the leading edge of the following material is determined in advance as a function of the moving tail edge position of the preceding material, the actual tail edge position of the preceding material is measured, the aiming distance between the tail edge of the preceding material and the leading edge of the following material is determined from the measured tail edge position of the preceding material and the function, and the actual position of the leading edge of the following material is controlled by the speed of the following material so as to obtain the distance, and the traveling speed of the joining apparatus is controlled so that determined point in the moving joining apparatus coincide with the tail edge of the preceding material, whereby the leading edge of the following material approaches and joins the tail edge of the preceding material while the preceding material is traveling.
Further, when the determined point in the joining apparatus coincides with the tail edge of the preceding material, the tail edge of the preceding material is restrained by restraint means, and after the restraint of the preceding material is completed, the speed of the following material is increased so that the following material be brought into contact with the tail edge of the preceding material.
Further, when the determined point in the joining apparatus coincides with the tail edge of the preceding material, the tail edge of the preceding materials restrained by restraint means, and when the distance between the tail edge of the preceding material and the leading edge of the following material becomes a predetermined value or less, the leading edge of the following material is restrained by the restraint means.
Further, after the restraint of the tail edge of the preceding material and the leading edge of the following material is completed, the tail edge of the preceding material and the leading edge of the following material are closed and brought into contact with each other until a predetermined load occurs.
Further, after the tail edge of the preceding material and the leading edge of the following material are closed and brought into contact with each other, they are separated and a predetermined distance is given.
Further, after the restraint of the tail edge of the preceding material is completed, the speed control of the joining apparatus is changed over to the speed control for making a tension of the preceding material a desired value.
Further, an image pickup device is provided on the joining apparatus so that the tail edge position of the preceding material be detected by the image pickup device.
Further, an image pickup device is provided on the joining apparatus so that both of the tail edge position of the preceding material and the leading edge position of the following material be detected by the image pickup device.
Also, the present invention provides hot rolling equipment which joins the tail edge of a preceding material and the leading edge of a following material to each other during traveling by using a movable joining apparatus after hot rough rolling, and feeds the materials to a finish rolling mill to roll the same, characterized in that an image pickup device, which can image both of the tail edge of the preceding material and the leading edge of the following material, is provided on the joining apparatus.
It is preferable that a preparatory period of time from when the tail edge of the preceding material is cut to when the leading edge of the following material is cut be taken so as to provide a distance between the tail edge of the preceding material and the leading edge of the following material.
Also, it is preferable that at the starting position of the joining apparatus, the distance between the tail edge of the preceding material and the leading edge of the following material have a determined value or less.
Also, the positions of the tail edge of the preceding material and the leading edge of the following material may be corrected according to the detection result of the image pickup device.